Dental handpiece

Abstract

A dental handpiece includes a drive shaft rotatably supported interiorly thereof, the drive shaft being hollow at least at the operating end thereof and having an internal thread; and a tubular friction collet in the hollow space having an external thread end evidencing in the inoperative condition thereof inwardly bent resilient tongues formed by a plurality of slits for the receipt and gripping of the shaft of an implement. The external thread of the friction collet is arranged at the implement-sided end thereof as in a threaded collet, the friction collet having an external conical surface and the hollow drive shaft having an internal conical surface cooperating with the external conical surface.

What is claimed is: 
     
       1. In a dental handpiece including a drive shaft rotatably supported interiorly thereof, said drive shaft being hollow at least at the operating end thereof and having an internal thread; and a tubular friction collet in the hollow space, having an external thread and evidencing in the inoperative condition thereof inwardly bent resilient tongues formed by a plurality of slits for the receipt and gripping of the shaft of an implement; the improvement comprising: the external thread of said friction collet being arranged at the implement-sided end thereof as in a threaded collet, said friction collet having an external conical surface and said hollow drive shaft an internal conical surface cooperating with said external conical surface, and wherein the internal conical surface of said hollow drive shaft widens to the shaft end at the implement-sided end region thereof, and the external conical surface of the friction collet widens at the implement-sided end region thereof towards that end of said collet. 
     
     
       2. Dental handpiece as claimed in claim 1, the internal thread of the hollow drive shaft being arranged at a distance from the implement-sided end of said drive shaft corresponding substantially to the length of the unthreaded portion of said collet. 
     
     
       3. Dental handpiece as claimed in claim 1, comprising key surfaces being arranged on the end of said hollow drive shaft remote from the implement end on the end of said friction collet proximate the implement. 
     
     
       4. Dental handpiece as claimed in claim 1, comprising key recesses being arranged in the end of said hollow drive shaft remote from the implement end in the end of said friction collet proximate the implement. 
     
     
       5. Dental handpiece as claimed in claim 3 or 4, comprising accessibility apertures in said handpiece being associated with said key, surfaces and recesses for the through passage of a key. 
     
     
       6. Dental handpiece as claimed in claim 1, said friction collet having unslitted end regions, said inwardly bent resilient tongues formed by axially parallel slits being located in the region intermediate said unslitted end regions.